1. Field of the Invention
The present invention relates to an air-fuel controller for use in carburetors of variable-venturi type.
2. Description of the Prior Art
In the conventional carburetors of variable-venturi type, as the amount of bleed is increased and decreased, the bleed comes into a mixing chamber by-passing the venturi portion of the carburetor, so that the position of a suction piston is changed in accordance with the change in the amount of bleed. In consequence, in the region where the flow rate of intake air is small as in the case of idling, the change in the amount of bleed causes a large change in the position of the suction piston, resulting in a large change in the air-fuel ratio of the mixture.
In consequence, an air-fuel ratio characteristic as shown in FIG. 1 is obtained to make the control of the air-fuel ratio extremely difficult.